Hi Florent,
Florent Hivert wrote:
>> I expected that the __getitem__ method for lazy family would
>>
>> 1) Check that the value given is (or can be coerced to) a key, and
>> 2) If a coercion is necessary, call the function on the coerced item.
> When calling Family(keys, functions) keys can be pretty anything: lists,
> tuple, parent in the category EnumeratedSets() or probably anythng which is
> iterable... We didn't assume that x in keys or keys(x) has any meaning. For
> example, I think the following is legal:
>
> sage: class toto(object):
> .....: def __iter__(self):
> .....: for i in [1,2,3]: yield i
> .....:
> sage: bla = toto()
> sage: Family(bla, lambda x: x^2)
> Lazy family (<lambda>(i))_{i in <__main__.toto object at 0x45f7f10>}
>
> Maybe this is too much permissive. So you are suggesting we should also
> require that keys should also implement __contains__. In what concerns
> coercion, please remember that a common usage is to lists as keys...
Thanks. I have some reasons why I would like keys to implement
__contains__, but I guess it will be easier to talk about this in
Toronto. I'd thought about the list case and don't have a really good
answer, although possibly the right behavior could somehow be decided
during __init__ ...
>> On a related note, the following *really* looks like a bug to me:
> This is clearly a bug ! Thanks for pointing this out.
This is now
http://trac.sagemath.org/sage_trac/ticket/8822
Cheers,
Jason
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